The present invention relates to a shoe having a construction allowing the shoe to be flexed, twisted and bent in various directions and a method of manufacture thereof.
Traditionally, a shoe's flexibility has been limited to a partial bending of a shoe to conform to the shape of the foot while walking in largely one direction. The ability of the shoe to flex, twist or bend in other directions in response to stress vectors from different directions has been restricted.
In conventional slip lasted shoes necessary rigidity and structural support has been provided, at least in part, by stitching the uppers of a shoe to a sock or cloth-foam material and stitching the combined uppers and sock with an outer wrap material. The sock or cloth-foam material extend the length of the shoe. This wrap material also secures in place foam material as well as insole boards. The wrap material with the stitched sock and upper are then cemented to the sole. This conventional structure of a shoe inherently limits its flexibility.
Designs of shoes which allow for increased flexibility while not sacrificing sufficient rigidity and sturdiness are desired in a shoe. Designs which eliminate the need for the insole board, or a shank and which free the upper and sock portion of the shoe from the rigidity of the cemented sole are desirable for the added flexibility and comfort they would provide to the wearer of the shoe.
The following terms or phrases used throughout this application will be understood to have the following meanings:
"EVA" refers to the chemical compound ethylene vinyl acetate.
"Forepart" refers to that portion of the shoe or sole forward of the heel.
"Last" refers to a form or mold which simulates the shape of a foot and which is used to shape and size a shoe.
"Lasting Allowance" refers to that portion of a shoe upper which extends under the bottom of a last past the perimeter of the sole line. The lasting allowance then provides a surface area below the last for purposes of cementing or stitching said upper to the shoe.
"Shank" refers to a rigid longitudinal member extending from the mid-heel through the arch portion of the shoe in the forepart of the shoe.
"Slip Last Construction" refers to constructing a shoe by forming a fully enwrapped shoe upper which conforms to the shape of the last. The last is then forced into the enclosed upper for forming and attaching to the sole.
"Sock" refers to a cloth-like material which extends along the length of the shoe above the sole.
"Wrap" refers to a material which covers and seals the seam or location where the upper and sock are attached. The wrap also provides a surface known as the lasting allowance which is cemented to the sole.